When a focused ion beam hits a sample, ions and electrons, commonly referred to as particles, are emitted from the interaction spot between the sample and the focused ion beam. Detecting the emitted particles is useful in analyzing and imaging the sample. Particle detectors, which can detect both positive and negatively charged particles, are described by: Strausser—U.S. Pat. No. 3,538,328; Gerlach et al.—U.S. Pat. No. 7,009,187; Ishitani Toru et al.—Japanese Patent Application Publication No. 07142022 A.
These detectors comprise a scintillator member, which is excited by electrons that either are emitted from the sample or are generated by conversion by an ion-to-electron converter. The converter is designed in such a way that positive ions impact the surfaces of an ion-to-electron converter such that secondary electrons are emitted from the converter surfaces, but negatively charged particles bypass the converter surfaces without impacting them. However, if negative ions fly through such a detector, they hit directly the scintillator surface and shorten its life. Therefore, there is a need for a detector that is capable to detect negative ions without compromising its service life.
Moreover, since the converter can amplify the number of particles emitted vs. the number of particles impinging, it would be an advantage, if the converter is capable of converting not only positive and negative ions to electrons, but also for converting primary electrons originating from the sample to secondary electrons, thereby amplifying the number of electrons too.